These are ranges see the link for more info

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps10081/data_sheet_c78-502660.html

Environmental Ranges

Normal Operating Conditions:

• -5ºC to +45ºC, up to 5,000 feet (1500 m)

• -5ºC to +40ºC, up to 10,000 feet (3000 m)

• -5ºC to +35ºC, up to 13,000 feet (4000 m)

Short-Term* Exceptional Operating Conditions:

• -5ºC to +55ºC, at sea level

• -5ºC to +50ºC, up to 5,000 feet (1500 m)

• -5ºC to +45ºC, up to 10,000 feet (3000 m)

• -5'C to +40'C, up to 13,000 feet (4000 m)

* Not more than following in one year period: 96 consecutive hours, or 360 hours total, or 15 occurrences